I suspect the spiritbond and condition aspects of the armoire reduce the amount of data that needs to be stored (which seems to be an ongoing problem in this game), since it can safely make the assumption that every item in every armoire is at 0% spiritbond and 100% condition.

Why worry about the spiritbond anyway? It's only useful for converting an item to materia, and the armoire is meant for items you intend to keep, not ones you plan to eventually destroy. It's also meant as long-term storage, mostly for things you want to save but not use often (such as holiday items).

I agree that more items should be on the list, however. Specifically, if it's a holiday item sold on the cash shop it needs to be on the armoire list the moment it shows up in the store (not several patches later).